Remote controlled devices and robots are in use in various aspects of science and industry, including automotive, construction, exploratory, salvage, painting, surface preparation, diagnostic and environmental cleanup industries. Increasingly, there are instances requiring remote controlled devices capable of surface traversing or climbing. Innovation in this field would be beneficial for elevated height surface climbing or when surfaces need to be decontaminated, cleaned, or coated with devices that reduce exposure of humans to contamination and to potentially hazardous elevated height working conditions. This has led to the development of a sub-field of remote controlled devices and robotics relating to surface traversing and climbing.
One family of climbing devices known in the prior art employs suction or magnetic elements mounted on movable frames. See, for example, U.S. Pat. No. 6,000,484 to Zoretich, U.S. Pat. No. 5,121,805 to Collie, U.S. Pat. No. 5,077,510 to Collie, and U.S. Pat. No. 6,105,695 to Bar-Cohen et al., the disclosures of which are incorporated by reference herein in their entirety. In some devices in this family, two or more frames inch along through caterpillar-like motions. The first frame's suction cups adhere while the second frame moves freely along, and then the second frame suction cups adhere. At this point, the first frame detaches, frees itself, and pulls its frame up to the second frame. This method of movement keeps repeating through an attaching/detaching process. This approach to surface traversal is slow, erratic, and does not lend itself to operations where smooth, continuous travel is needed (such as cleaning, coating removal, decontamination surveys, etc.). Further, it has limitations in terms of surface obstacles that it can encounter and circumvent.
A second family of climbing devices known in the prior art employ suction cups mounted on endless tracks. Devices employing suction cups on endless tracks require relatively flat surfaces because a large percentage of the suction cups must be in intimate sealing contact with the surface to affect adhesion. On rough or uneven surfaces, a large percentage of the suction cups are unable to make firm contact, thus the devices lose adhesion. Such devices are most appropriate for climbing the skin of large aircraft, where the surface is relatively smooth. Such a device would not work well on spalled concrete, where the surface is very uneven, or on many bridge structures where the surfaces include many plates bolted together. The large bolts and the unevenness of the plates render the suction cup adhering device ineffectual at negotiating these surfaces. The valving on this type of device is typically very complex, since the vacuum is only applied to the cups that are firmly secured and not applied to the cups that are not firmly secured to the surface. Otherwise, too much vacuum loss will occur. This has dramatically limited the use of this type of design to applications justifying a very complex and costly device and/or where relatively flat, smooth surfaces exist, such as commercial aircraft skins.
A third family of climbing devices known in the prior art incorporate a large suction chamber surrounded by a fixed seal partition that is dragged or slid over the surface being traversed. See, for example, U.S. Pat. No. 4,926,957 to Urakami, U.S. Pat. No. 5,536,199 to Urakami, U.S. Pat. No. 5,752,577 to Urakami, U.S. Pat. No. 6,102,145 to Fischer, and U.S. Pat. No. 3,268,023 to Napoli, the disclosures of which are incorporated by reference herein in their entirety. Wheels or endless tracks move devices in this family of machines. While the vacuum force in the large chamber affects adhesion to the surface, premature and excessive wear on the seal partition has lead to numerous attempted improvements in seal technology, such as vibrating seals or easily replaceable seal partitions. These devices, however, are limited to flat or relatively flat surfaces, because the seal partition, even those made from rubber or inflated diaphragms, are dragged over the surface. These devices cannot negotiate surface obstructions such as large bolts or plates without a suction loss. This, in turn, can result in the device falling from the surface. Furthermore, the dragging of the seal partition results in rapid seal wear and deterioration, necessitating frequent seal replacement. Of concern is predicting when the seal will fail from wear. The habitual failure of seals in this family of devices presents danger and reliability concerns, limiting their commercial acceptance and usage.
Thus, all the previous prior art examples exhibit limitations that render them ineffective in many practical, commercial conditions. While such devices do provide various systems for adhering to surfaces, in actual field operation, their limitations have restricted their uses to generally flat, obstacle-free surfaces. They cannot traverse surfaces commonly found in many real life settings. Accordingly, there exists a need for climbing devices that can traverse surfaces such as spalled concrete, corroded metal, or surfaces with bolts, plates, weldments, surface obstacles, sharp protrusions, or obstructions breaking the plane of the surface or where the surface is uneven.
Science and industry seek remote controlled or robotic devices that can effectively traverse a wide range of surfaces and surface conditions. In particular, devices presenting a high level of reliability, resistance to seal failures, and the ability to overcome uneven surfaces, common surface protrusions, or real life surface conditions are needed. Therefore, a need exists in the art to develop reliable climbing surface traversing devices capable of engaging a wide array of surface types and surface conditions.